Scientists have shown for the first time that insects, like
mammals, use vision rather than touch to find footholds. They made the
discovery thanks to high-speed video cameras – technology the BBC uses to
capture its stunning wildlife footage – that they used to film desert locusts
stepping along the rungs of a miniature ladder.
The study sheds new light on insects' ability to perform
complex tasks, such as visually-guided limb control, usually associated with
mammals.
According to lead author Dr Jeremy Niven of the University of Cambridge: "This is another example
of insects performing a behaviour we previously thought was restricted to
relatively big-brained animals with sophisticated motor control such as humans,
monkeys or octopuses."
Because insects such as bees and flies spend a lot of time
flying, most research has concentrated on how insects use vision during flight.
Many insects that spend a lot of time walking, such as stick insects, crickets
and cockroaches have relatively small eyes and use long antennae to 'feel'
their way through the environment.
Locusts spend time both walking and flying, and have short
antennae and large eyes, which made Niven wonder whether they used vision to
find footholds.
To answer this question, the team built a miniature
locust-sized ladder and filmed the locusts walking along it. They counted the
number of times the locusts missed steps, comparing the number of mistakes they
made in different situations.
"By combining all these different experiments, we
showed that locusts use vision to place their legs. We showed that when locusts
can't see one front leg they stop using that leg to reach to the next ladder
rung, favouring the leg they can see," Niven explains.
"Big-brained mammals have more neurons in their visual
systems than a locust has in its entire nervous system, so our results show that
small brains can perform complex tasks. Insects show us how different animals
have evolved totally different strategies for doing similar tasks," he
says.
As well as illustrating how insects can achieve similar
results to mammals by using simpler mechanisms, the findings deepen our
understanding of locusts' neural circuits.
This is important because locusts have been a model organism
for studying limb control for the past 40 years. Insects such as the locust
have been crucial to many breakthroughs in neuroscience, and insects are often
the inspiration for limb control in robotics.
The results are published this month in Current Biology.
Original
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Study
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